1. Field of the Invention
The present invention relates to a rearview monitoring apparatus for a vehicle which is carried on the vehicle and displays rearview images taken by a camera device to occupants in the vehicle.
2. Description of Related Art
Conventionally, a rearview monitoring apparatus for a vehicle for taking rearview images of the vehicle by a camera and displaying the rearview images as supplementary information for a driver by a monitoring device which is located near a driver's seat is known.
As such an apparatus, for example, an apparatus which comprises a camera for taking a rearview image of the vehicle and a superposing device which displays a vehicle width line indicating the width of the vehicle and a distance line indicating the distance of an obstacle from the vehicle in an image taken by the camera is disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 10-151991.
This apparatus changes the line width and the line color of the distance line in the rearview image of the vehicle which is displayed by the superposing device according to the distance of the obstacle from the vehicle and provides accurate information such as distance to the obstacle and the vehicle width line to a occupant in the vehicle by adjusting the display position of the distance line and the vehicle width line according to inclination of the vehicle and the change in the vehicle height. Also, in this apparatus, the occupants in the vehicle acknowledge a positioning relationship of the vehicle to the obstacle around the vehicle by displaying a rear end part of the vehicle in the superposed image.
FIG. 14 is an example of a image view which is displayed by such a conventional rearview monitoring apparatus for a vehicle as explained above. In such a conventional apparatus, a rear end 51 of a bumper which is taken in a viewing angle of the camera for acknowledging the position of the vehicle, a tire width line 55 indicating a track of tire passage, and a distance index such as 1 m line 52, 2 m line 53, and 3 m line 54 indicating a distance to the obstacle from the rear end 51 of the bumper are displayed in the rearview image.
However, it was not possible to acknowledge sufficiently the positioning relationship between the vehicle and the obstacle around the vehicle when a protruding object such as a spare tire is attached on the rear end of the vehicle, even though it was possible to acknowledge the positioning relationship between the vehicle and the obstacle around the vehicle by displaying the rear end part of the vehicle in the rearview image of the conventional apparatus.
That is, when a spare tire 23 is attached on the rear end of the vehicle as shown in FIG. 15 which shows a conventional example of a positioning relationship of the vehicle 21 and a charge coupled device (hereinafter called a CCD) camera 2, the situation around the vehicle cannot be displayed because a region in a dead angle increases when the spare tire 23 is in the rearview image. Therefore, the attaching position and the angle of view of the CCD camera 2 are often adjusted so that the spare tire 23 is not displayed in the rearview image as shown in FIGS. 16 and 17 (modified example in the conventional example). In such a case, the spare tire 23 is not displayed in the rearview image. For example, as shown in FIG. 18, the positioning relationship of the obstacle 24 around the vehicle and the spare tire 23 could not be understood according to a limit line (rear end 51 of the bumper) displayed in the rearview image.
Also, even if a portion of the spare tire 23 could be displayed in the rearview image, the region in the dead angle increased and the CCD camera could not take an image of a rear end portion of the spare tire directly as explained above. Thus, there was a problem in that it was impossible to understand the positioning relationship of the obstacles around the vehicle and the spare tire 23 according to the rearview image sufficiently.
Also, when displaying the positioning relationship of the distance line and the actual vehicle, a space for opening a tailgate (a back door of the vehicle which opens over the rear end of the vehicle) was not taken into account. Therefore, there was sometimes a problem in that the tailgate of the vehicle could not be opened after the vehicle was parked.
Also, on the other hand, there were problems as follows. It was possible to park the vehicle 21 extremely near an obstacle 24 by using a conventional rearview monitoring apparatus for a vehicle as long as the tailgate 123 which was provided to the vehicle 21 was not supposed to be opened similarly to the positioning relationship of the vehicle 21, a rear end portion of the bumper 22 (rear end 51 of the bumper in FIG. 8) taken by a CCD camera 2, and the obstacles 24 around the vehicle 21 as shown in FIG. 19. However, when the vehicle 21 was parked while the tailgate 123 provided to the vehicle 21 was supposed to be opened, it was not possible to understand the positioning relationship of the obstacles 24 around the vehicle 21 and the opened tailgate 123 according to the limit line (rear end 51 of the bumper) displayed in the rearview image as shown in FIG. 20. Therefore, the occupants in the vehicle 21 could not park the vehicle 21 near the obstacles 24 while having a space for the tailgate 123 to open.